1. Field of the Invention
The present invention relates to an optical module and, more particularly, to an optical module capable of stably transmitting an optical signal.
2. Description of the Related Art
An optical module is an optical device to be used in an optical communication and, more specifically, an assembly in which an optical fiber or an optical waveguide is aligned with respect to the optical axis of an optical device (light emitting device or light receiving device) and connected thereto. In the optical module, an electrical signal is converted into an optical signal to be transmitted to the optical fiber or an optical waveguide, or an optical signal received from the optical fiber or the optical waveguide is converted into an electric signal to be transmitted.
An optical fiber is formed of a slender single wire or a bundle of wires of glass or synthetic resin. An optical fiber made of glass is formed to a thickness of 3xcx9c60 xcexcm and an optical fiber made of synthetic resin is formed to a thickness of 100 xcexcmxcx9c10 mm. Also, an optical fiber is composed of a core, which has a high refractive index and is formed on a central portion of the optical fiber, and a clad, which has a low refractive index and is formed on an outer portion of the optical fiber. A light, which is incident on an optical fiber, is totally reflected from an interface between the core and the clad and is propagated only to the core. The optical fiber is a light communication path in which a relay interval can be lengthened while a loss in light is minimized; the optical fiber is used in the optical communication as described above.
The optical waveguide is included in a housing in which the optical fiber is made of silicon or polymer, and is used mainly for transmitting an optical signal over a short distance.
For instance, in a conventional optical module disclosed in U.S. Pat. No. 5,434,939, an optical fiber is inserted into a guiding hole, which is formed to face a surface emitting laser in a substrate having the surface emitting laser, and fixed by an adhesive.
FIG. 1 shows a structure of a conventional optical module. In FIG. 1, the optical module includes: an electric circuit substrate 11 with anodes 16 and insulator film 17; a light emitting chip 12 installed on the electric circuit substrate 11 and including first and second layers 12A and 12B; a surface emitting laser 14, which has a p-type mirror 21, an active layer 22 and an n-type minor 23, and which is installed in the first layer 12A of the light emitting chip 12 and electrically connected to the electric circuit substrate 11; an open guiding hole 19 aligned with respect to the surface emitting laser 14 and formed in the second layer 12B of the light emitting chip 12, i.e. the second layer 12B comprises a semiconductor substrate; and an optical fiber 18 optically connected to the surface emitting laser 14 and inserted into the guiding hole 19.
The voltage of the surface emitting laser 14 is amplified by a bipolar transistor 15 installed at a lower portion thereof, comprising a collector 25, a base 26 and an emitter 27. The amplified voltage is transmitted to the surface emitting laser 14 and a laser beam is emitted in the surface emitting laser 14. As a result, an optical signal is generated and travels toward the optical fiber 18.
However, in the above conventional optical module, an adhesive 20 used to fasten the optical fiber 18 in the guiding hole 19 may leak in the guiding hole 19. If this happens, an optical signal generated from the surface emitting laser 14 may be blocked from transmission to the optical fiber 18 by the adhesive 20. Further, when the optical fiber 18 is not firmly fastened in the guiding hole 19, the position of the optical fiber 18 will change, thereby preventing an optical signal from being entirely transmitted to the optical fiber 18 from the surface emitting laser 14.
In addition, the conventional optical module is configured in that the guiding hole 19 is installed in the semiconductor substrate 12B, which requires an additional manufacturing process. Accordingly, the conventional optical module is difficult to make and manufacture.
To solve the above-described problem, it is an aspect of the present invention to provide an optical module, which is mass-produced at a low cost and is extensively used, and is capable of transmitting an optical signal stably and completely.
An apparatus consistent with the present invention relates to an optical module comprising an optical device which converts an optical signal into an electric signal, and vice versa, a light guide member having a core and a clad for forming an interface from which the optical signal is reflected where the core is a path of the optical signal generated by the optical device, and the clad is installed outside the core, and a holder formed on an end of the light guide member, for fixing the alignment of the optical device and the light guide member along the optical axes with respect to the same point, the holder through which the optical signal can penetrate.
To further solve the above-described problem, it is an aspect of the present invention to provide an optical module comprising an optical device which converts an optical signal into an electric signal, and vice versa; and a light guide member and a holder, through which the optical signal generated by the optical device is transmitted, the light guide member and the holder being attached to the optical device, wherein the light guide member and the holder comprise a core, which is a path of an electric signal, and a clad formed outside the core, wherein the core and the clad form an interface from which the optical signal is reflected.
The optical device is one of a light emitting device and a light receiving device.
The light guide member is formed of an optical fiber or optical waveguide.
The holder is formed of poly-methylmethacrylate (PMMA) or epoxy.
The optical module may further include terminals as paths for transmitting and receiving electrical signals from the optical device.
An optical module according to the present invention has advantages of stably transmitting an optical signal because an optical device and a light guide member are fastened by a holder formed of a medium having a light transmittance.